Patient-specific convertible guides

ABSTRACT

A convertible patient-specific guide for use in arthroplasty has a body having a patient-specific three-dimensional undersurface closely mateable engageable in only one position with a corresponding joint surface of a specific patient. The convertible guide includes patient-specific guiding formations extending from the body and configured for guiding both a total arthroplasty of the joint and a partial arthroplasty of the joint, such that the arthroplasty to be performed is intraoperatively changeable.

FIELD

The present teachings relate to patient-specific guides for orthopedicsurgery and in particular to patient-specific guides that areconvertible to accommodate intraoperative changes of a preoperativesurgical plan for a patient.

INTRODUCTION

The present teachings relate to devices and methods for enabling thesurgeon to change a preoperative surgical plan for a specific patientintraoperatively from a first surgical procedure to a second surgicalprocedure without requiring separate patient-specific guides that areindividually dedicated to each procedure. For example, the preoperativeplan for the patient may be designed for a partial knee arthroplasty,but intraoperatively, the surgeon may make a determination to perform atotal knee arthroplasty. The present disclosure provides variousexemplary guides for allowing the surgeon to convert from one surgicalprocedure to another intraoperatively with efficiency, ease and costeffectiveness.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide a convertible patient-specific guide foruse in arthroplasty. The convertible guide has a body having apatient-specific three-dimensional undersurface closely mateable in onlyone position with a corresponding joint surface of a specific patient.The convertible guide includes patient-specific guiding formationsextending from the body and configured for guiding both a totalarthroplasty of the joint and a partial arthroplasty of the joint, suchthat the arthroplasty to be performed is intraoperatively changeable.

The present teachings also provide a convertible patient-specific guidethat includes a body having a patient-specific three-dimensionalundersurface closely mateable in only one position with a correspondingfemoral knee joint surface of a specific patient. The convertiblepatient-specific guide includes patient-specific guiding formationsextending from the body and configured for guiding a total kneearthroplasty of the joint. The convertible patient-specific guidefurther includes a connector extending from the body. The connector canbe coupled with a patient-specific unicondylar knee guide forintraoperatively converting a unicondylar partial knee arthroplasty to atotal knee arthroplasty.

The present teachings provide a method of intraoperatively selectingbetween a partial knee arthroplasty and total knee arthroplasty. Themethod includes mounting a patient-specific three-dimensional surface ofa patient-specific guide in a unique position mating to a correspondingsurface of a distal femoral bone. The patient-specific guide includes ananterior portion and a distal portion including a patellofemoral guideportion. The method includes selecting one of a total knee arthroplastyand a partial knee arthroplasty. If total knee arthroplasty is selected,first and second covers are removed from corresponding first and seconddistal guiding bores and first and second distal pins are registeredthrough the first and second distal guiding bores. If partial kneearthroplasty is selected, the anterior portion is removed along afrangible groove and the patellofemoral guide portion for partial kneearthroplasty.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of a patient-specific convertible guideselectively usable either for a total knee arthroplasty or apatellofemoral procedure as determined intraoperatively by the surgeonaccording to the present teachings;

FIG. 1A is a perspective view of an exemplary patellofemoral implant;

FIG. 2 is a plan view of a patient-specific patellofemoral guideaccording to the present teachings;

FIG. 3 is an environmental view of a patient-specific convertible guidewith an anterior removable section, such that the convertible guide isselectively usable either for a total knee arthroplasty or apatellofemoral procedure as determined intraoperatively by the surgeonaccording to the present teachings;

FIG. 3A is a detail of the patient-specific convertible guide of FIG. 3;

FIG. 4 is the patient-specific convertible guide of FIG. 3 with theanterior section removed and shown with a resection guide according tothe present teachings;

FIG. 5 is an environmental view of a patient-specific guide for partialknee arthroplasty shown with a convertible guide for total kneearthroplasty according to the present teachings;

FIG. 6A is a perspective view of a patient-specific guide for partialknee arthroplasty according to the present teachings;

FIG. 6B is another perspective view of the patient-specific guide forpartial knee arthroplasty of FIG. 6A;

FIG. 6C is a perspective view of a drill template for thepatient-specific guide for partial knee arthroplasty of FIG. 6Aaccording to the present teachings;

FIG. 6D is an environmental view of a femoral bone with a resectionblock supported in holes drilled in the bone using the drill template ofFIG. 6C according to the present teachings;

FIG. 7 is a bottom plan view of a patient-specific femoral bone modelaccording to the present teachings; and

FIG. 8 is an elevated view of a patient-specific tibial bone modelaccording to the present teachings.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully with reference tothe accompanying drawings.

The present teachings generally provide various patient-specific orcustom guides and/or other instruments and devices for total and/orpartial arthroplasty including unicondylar knee arthroplasty andpatellofemoral compartment arthroplasty. More specifically, the presentteachings provide various customized and patient-specific guides andother devices that enable the surgeon to change a preoperative surgicalplan for a specific patient intraoperatively from a first surgicalprocedure to a second surgical procedure without requiring separatepatient-specific guides dedicated to each procedure. For example,preoperatively, a partial knee arthroplasty (PKA) may have beencontemplated for a specific patient, but intraoperatively observedconditions may lead the surgeon to perform a total knee arthroplasty(TKA) instead.

The present teachings provide various exemplary guides, devices andmethods for allowing the surgeon to convert from one surgical procedureto another intraoperatively while maintaining the benefit of apreoperative plan and the use of patient-specific guides. In someembodiments, for example, a single patient-specific guide can be a dualpurpose/dual function guide that can provide alignment guidance for bothTKA and PKA procedures. In some embodiments, a single patient-specificguide can be convertible from one procedure to another. Unless there isa need to distinguish between particular embodiments, patient-specificguides designed for dual surgical procedures or convertible from onesurgical procedure to another intraoperatively will be referenced as“convertible” guides. Patient-specific convertible guides are describedbelow in further detail, although non-custom convertible guides can alsobe used.

The patient-specific convertible guides and other associated instrumentsand devices can be used either with patient-specific or withconventional/standard (i.e., non-custom) femoral or tibial implantcomponents. Generally, patient-specific devices can be designedpreoperatively using computer-assisted image methods based onthree-dimensional images of the patient's knee anatomy reconstructedfrom MRI, CT, ultrasound, X-ray, or other three- or two-dimensionalmedical scans of the patient's anatomy and in some cases complementedwith digital photography methods and/or anthropometry databases. VariousCAD programs and/or software can be utilized for three-dimensional imagereconstruction, such as software commercially available, for example, byMaterialise USA, Plymouth, Mich.

In the preoperative planning stage for a joint replacement or revisionprocedure, such as, for example, total knee arthroplasty (TKA) orpartial knee arthroplasty (PKA), or patellofemoral compartment (PFR)arthroplasty, imaging data of the relevant anatomy of a patient can beobtained at a medical facility or doctor's office, using one of medicalimaging methods described above. The imaging data can include, forexample, various medical scans of a hip, knee, ankle or other joint orrelevant portion of the patient's anatomy, as needed for joint modeling,mechanical/alignment axis determination or for other alignment purposes.The imaging data obtained and other associated information can be usedto construct a three-dimensional computer image of the joint or otherportion of the anatomy of the patient. An initial preoperative plan canbe prepared for the patient in image space and can include bone or jointpreparation, planning for resections, milling, reaming, broaching,implant selection and fitting, as well as designing patient-specificguides, templates, tools and alignment methods for the surgicalprocedure.

In the context of the present teachings, patient-specific guides andimplants are generally configured to match the anatomy of a specificpatient and are generally formed using computer modeling based on thepatient's reconstructed three-dimensional anatomic image. Thepatient-specific guides have an engagement surface that is made toconformingly contact and match a three-dimensional image/model of thepatient's bone surface (with or without cartilage or other soft tissue),by the computer methods discussed above. In this respect, apatient-specific guide can nestingly mate with the corresponding bonesurface (with or without articular cartilage) of the specific patient inonly one position. The patient-specific alignment guides can includecustom-made (patient-specific) guiding formations, such as, for example,guiding bores or cannulated guiding posts or cannulated guidingextensions or receptacles that can be used for supporting or guidingother instruments, such as drill guides, reamers, cutters, cuttingguides and cutting blocks or for inserting pins or other fastenersaccording to a surgeon-approved pre-operative plan.

The customization of the guiding formations is designed during thepreoperative plan to provide templates for guiding cutting tools toperform the planned drilling, resections or other surface preparationaccording to the preoperative plan. For example, the guiding formationscan provide spatial orientation and positions for drilling of holes toinsert pins or other supporting connectors for mounting thecorresponding cutting tools for the preparation of the bone. Thepatient-specific guides can be used in minimally invasive surgery, andalso in surgery with multiple minimally-invasive incisions. Variousalignment guides and pre-operative planning procedures are disclosed incommonly assigned and co-pending U.S. patent application Ser. No.11/756,057, filed on May 31, 2007, U.S. patent application Ser. No.12/211,407, filed Sep. 16, 2008; U.S. patent application Ser. No.11/971,390, filed on Jan. 9, 2008, U.S. patent application Ser. No.11/363,548, filed on Feb. 27, 2006; U.S. patent application Ser. No.12/025,414, filed Feb. 4, 2008, U.S. patent application Ser. No.12/571,969, filed Oct. 1, 2009, and U.S. patent application Ser. No.12/955,361, filed Nov. 29, 2010. The disclosures of the aboveapplications are incorporated herein by reference.

The outcome of the initial fitting is an initial surgical plan that canbe printed or provided in electronic form with corresponding viewingsoftware. The initial surgical plan can be surgeon-specific, when usingsurgeon-specific alignment protocols. The initial surgical plan, in acomputer file form associated with interactive software, can be sent orotherwise provided over the internet or other cloud/web type ofcommunication to the surgeon, or other medical practitioner, for review.The surgeon can incrementally manipulate the position of images of theimplant components in an interactive image of the joint. Additionally,the surgeon can select or modify resection planes, types of implants andorientation and position of implant insertion. After the surgeonmodifies and/or approves the surgical plan, the surgeon can send orelectronically communicate or save in an internet space or dedicatedserver the final, approved preoperative plan that can be accessed by themanufacturer. Patient-specific guides and other tools for the approvedpreoperative plan can be manufactured and included with the selectedimplants and other instruments or devices in a kit for the specificpatient, specific procedure and specific surgeon. In addition,patient-specific physical models of the corresponding bone portions canbe prepared for physical visualization and trial testing of the bone, asdiscussed below. The various patient-specific guides discussed hereincan be made of any biocompatible material, including metal or plastic.Generally, the patient-specific guides are disposable and made oflightweight materials, including polymers.

Referring to FIG. 1, an exemplary dual purpose, (“convertible” forshort) patient-specific guide 100 is shown mounted on the correspondingpatient's distal femur 80. The convertible guide 100 includes alight-weight body 102 having an inner or anatomy engaging surface 104that is designed during the preoperative plan of the patient to bepatient-specific, i.e., to nestingly mate with the patient's jointsurface, such as portions of the anterior and distal surfaces of thepatient's femur 80 (with or without articular cartilage) in only oneposition, as determined by the preoperative plan. The convertible guide100 can include a visualization window/opening 106 and first and seconddistal guiding formations 108 defining distal guiding bores 110 forguiding corresponding distal alignment pins (not shown). The convertibleguide 100 can also include first and second anterior guiding formations112 defining anterior guiding bores 114 for guiding correspondinganterior alignment pins (not shown). The distal and anterior guidingformations 108, 112 are designed to have orientations and positions forguiding pins or other connecting members on which to support variouscutting instruments to perform the resections determined in apreoperative plan for an optional total knee arthroplasty. A fifthpatellofemoral guiding formation 116 having a patellofemoral guidingbore 118 is also provided on the convertible guide 100 for guiding anoptional partial knee replacement, such as a patellofemoral replacementin which a patellofemoral replacement system is used, such as, forexample, the Vanguard® PFR Partial Knee, commercially available fromBiomet Manufacturing Corp., Warsaw, Ind. An exemplary PFR implant 50having a stem 52 for attachment to the patellofemoral compartment of thebone is illustrated in FIG. 1A. The various guiding formations can be inthe form of tubular structural elements, such as, for example, conicalportions or cylindrical portions with cut-outs or windows, and such thatthe guiding formations can provide guiding support for drilling holes inthe bone with reduced weight and improved visibility.

More specifically, the patient-specific convertible guide 100 isdesigned during the preoperative plan for the specific patient to guidea first type of arthroplasty selected by the surgeon, but is alsocapable to be used for and guide a second type of arthroplasty, when thesurgeon determines intraoperatively that the second type is indicatedbased on intraoperative conditions or other intraoperativeconsiderations. In the exemplary embodiment of FIG. 1, the convertibleguide 100 can be selectively used either for total knee arthroplasty(TKA) or for a partial knee arthroplasty, such as a patellofemoral (PFR)arthroplasty that replaces only the patellofemoral compartment of theknee joint. Accordingly, the convertible guide 100 can be usedintraoperatively for total knee arthroplasty or for partialpatellofemoral arthroplasty based on an intraoperative determination bythe doctor.

Further, the convertible guide 100 can be used for a patellofemoralarthroplasty even though the preoperative plan calls for patellofemoralarthroplasty and no intraoperative change in plan is envisioned, i.e.,when no change from a patellofemoral to total knee arthroplasty iscontemplated. In such case, the patient-specific convertible guide 100can still provide improved alignment guidance that requires fewerintraoperative adjustments than conventional trialing and otherpatellofemoral (PFR) guides, as described below.

The convertible guide 100 can be attached to the femur using anteriorpins through the anterior bores 114. The distal guiding bores 110 can becapped or otherwise obstructed with removable, severable,frangible/breakable covers 120, such that no distal holes are drilledthrough the distal guiding bores 110, unless the surgeon opts for atotal knee arthroplasty procedure, in which case the covers 120 areremoved or snapped off or twisted off. A patellofemoral pin hole 122 canbe drilled into the femur through the patellofemoral guiding bore 118.

The convertible guide 100 can be removed and a PFR-specific guide 150can be guided by and pinned on to the femoral bone using thepatellofemoral hole 122, as shown in FIG. 2. The PFR guide 150 can bepatient-specific and also designed based on the preoperative plan forthe specific patient. The PFR guide 150 can include a body 152 having abone-engagement undersurface 154 that can nestingly mate and conform tothe three-dimensional patellofemoral compartment of the patient's distalfemur 80. The PFR guide 150 can include two distal guiding formations158 having distal guiding bores 160 corresponding to the distal guidingbores 110 of the convertible guide 100 and a patellofemoral guidingformation 166 with a patellofemoral bore 168 corresponding to thepatellofemoral formation 116 and patellofemoral bore 168 of theconvertible guide 100 of FIG. 1. The distal guiding bores 160 can becovered with covers 120, which can be removed, if a TKA procedure isintraoperatively selected by the surgeon instead of the PFR procedure.The PFR guide 150 can also include a supporting structure 170 havingfirst and second slots, openings or other connecting structural features172 for removably connecting and aligning a femoral resection block 180(shown in FIG. 4) to the PFR guide 150. In the embodiment illustrated inFIG. 4, the femoral resection block 180 includes first and second legs182, 184 that can be slidably inserted into the corresponding slots 172of the PFR guide 150. The femoral resection block 180 can also include acutting guide 184 for guiding a cutting instrument, such as a blade, toperform an anterior resection. The cutting guide 184 can have a curvedor J-shaped profile for wrapping around the medial side of the femur 80to provide access for the anterior resection. The femoral resectionblock 180 can also include an aperture 186 for optionally connecting ananterior stylus (not shown), for confirming sizing.

The patient-specific convertible guide 100 and the patient-specific PFRguide 150 are prepared during the preoperative plan so that both areshipped to the surgeon and can be used together. For example, theconvertible guide 100 provides all the functions of a patient-specificTKA alignment guide and also includes the additional feature of a PFRguiding formation 116 for drilling the PFR drill hole 122. In thisrespect, the convertible guide 100 can provide alignment guidance forlocation or reference pins for use either in a TKA procedure or apartial knee arthroplasty (PKA), such as a PFR procedure. When a TKAprocedure is intraoperatively selected, alignment or location pins areplaced into the bone through the anterior and distal guiding bores 114,110 for supporting a distal resection guide, a four-in one cutting blockor other cutting block for an anterior resection, chamfer resections,etc., as described in commonly assigned and co-pending U.S. patentapplication Ser. No. 11/756,057, filed on May 31, 2007, incorporatedherein by reference.

Referring to FIGS. 3-5, in some embodiments, the functions ofconvertible guide 100 and PFR guide 150 are incorporated in a singlepatient-specific convertible guide 200. The same reference numerals areused to denote common elements between the convertible guide 200 andguides 100 and 150. The convertible guide 200 is a frangible, breakableor severable guide with a fracture line or groove or other separatorelement 230. The separator element 230 facilitates separating a first oranterior portion 202 of the convertible guide 200 from a second portion250, which, when severed or separated from the first portion 202,defines a standalone, complete guide that is interchangeable with thePFR guide 150 (marked herein with the same numeral numbers as the PFRguide 150). The first portion 202 includes a patient-specific matingundersurface 204 that can be mounted in only one position and mate in athree-dimensional way with the patient's corresponding anatomy. Thefirst portion 202 can include the anterior guiding formations 112 andcorresponding bores 114 and the window 106.

The convertible guide 200 provides the surgeon with various options forintraoperative use. For example, in one option, the covers 120 can beremoved from the distal guiding bores 160, and the convertible guide 200can be used as a patient-specific TKA guide providing alignmentreferences and registration for anterior pins through the anteriorguiding bores 114 and for distal pins through the distal guiding bores160. In another option, the convertible guide 200 can be used in a PFRprocedure instead of the combination of guides 100 and 150 of FIGS. 1and 2 discussed above. In this respect, the PFR portion 250/150 can besnapped off either before or after registration to the bone of thepatient. For example, the entire convertible guide 200 can be firstuniquely mated to the patient's femoral bone 80 and pinned on the femur80. Then, the first portion 202 can be snapped off and removed, leavingthe second portion 250 or PFR guide 150 mounted on the femoral bone 80to be used with the anterior resection block 180 to perform the anteriorresection, as discussed above in reference to FIG. 4. Another option isto snap off the anterior portion 202 before the convertible guide 200 ismounted on the femoral bone 80, such that only the PFR portion 250 orPFR guide 150 is mounted on the femoral bone 80, using thepatient-specific undersurface 154 for registration, in view of the factthat the undersurface 154 is designed preoperatively to mate with thecorresponding anatomy of the patient in only one position, as discussedabove.

Referring to FIG. 5, a patient-specific convertible guide 400 forconverting partial (unilateral or unicondylar) knee arthroplasty tototal knee arthroplasty is illustrated. The convertible guide 400 can beused with a partial or unilateral or unicondylar femoral guide 300,which can be patient-specific (customized for the patient) or not(standard, non-custom), as shown in FIGS. 6A-6D. The unilateral kneeguide 300 illustrated in FIGS. 5, 6A and 6B is patient-specific andincludes a body 302 with a three-dimensional patient-specificundersurface 304 designed during the preoperative plan to conform tounilaterally, i.e., to only one of the medial and lateralsurfaces/femoral condyles of the femoral bone 80 of the patient in onlyone position. The body 302 and the undersurface 304 can extend from adistal portion 312 over one of the lateral or medial femoral condyles toan anterior portion 314. The unilateral knee guide 300 can be markedwith the name of the patient and the corresponding knee and condyle,such as “RIGHT/MEDIAL”, for example, for convenient preoperative andintraoperative identification. A guiding formation 308 extends generallyfrom the distal portion 312. The guiding formation 308 defines anelongated slot 310 with a tapered inner peripheral wall 306. A drilltemplate 320 can be provided for guiding a drill to form one or moreholes in the bone as determined during the preoperative plan. Anexemplary drill template 320 is illustrated in FIG. 6C in the form of aninsert with a tapered peripheral wall 322 that can mate with the innerperipheral wall 306 of the elongated slot 310. The drill template 320can include a number of guiding holes 324 at a patient-specific locationand configuration relative to the unilateral knee guide 300. Two guidingholes 324 are illustrated in FIG. 6C. Depending on the procedure, thesurgeon can determine intraoperatively whether to drill correspondingholes 86 in the bone for supporting a resection block 350, as shown inFIG. 6D. In some embodiments, several patient-specific drill templates320 having different configurations of guiding holes 324 can beprovided. The drill templates 320 can be, for example, metallic foradded stability, or plastic with sufficient thickness to providestability.

Intraoperatively, the surgeon can mount the unilateral knee guide 300 onthe specified knee and condyle of the patient in a unique position basedon the preoperative plan for the patient. If the surgeon determines toproceed with the partial knee procedure, then the drill template 320 canbe fitted over the elongated slot 310 and holes 86 for guiding pins canbe drilled into the bone 80. The unilateral knee guide 300 can then beremoved, and the holes 86 can be used to mount rods or pins 352 of acutting instrument, such as the resection block 350 illustrated in FIG.6D, in a position predetermined by the holes 86 drilled in the bone. Theresection block 350 is then positioned for performing a resection alonga plane 88 for excising the posterior facet of the femoral condyle at alocation and orientation determined during the preoperative plan for thepatient. The surgical technique can then follow standard procedures,such as, for example, the surgical technique associated with the Oxford®Partial Knee, which is commercially available by Biomet ManufacturingCorp., Warsaw, Ind., and described at Biomet's website.

Alternatively, the surgeon may determine intraoperatively that a totalknee arthroplasty (TKA) is indicated instead of the initially plannedpartial knee arthroplasty (PKA). The convertible guide 400 can then beplaced over the already mounted partial knee guide 300 to providepatient-specific registration for a total knee arthroplasty based on thepreoperative plan for the patient. The convertible guide 400 is alightweight guide already sized and shaped for the specific patient inconjunction with the partial knee guide 300. The convertible guide 400is designed to mate and align with the patient's femoral bone 80 whenmounted over the partial knee guide 300 based on the preoperative planfor the patient and in anticipation of a possibility that TKA may beintraoperatively selected instead of the initially planned PKA.

Referring to FIG. 5, in some embodiments, the convertible guide 400 canform a frame of interconnected elongated members including lateral andmedial elongated members 402, 404 for the corresponding femoralcondyles, an anterior elongated member 406 and a distal elongated member408. The interconnected elongated members 402, 404, 406, 408 cangenerally follow and conform the patient's three-dimensional geometry,while their corresponding undersurfaces 403, 405, 407, 409, spatialdimensions and orientations are patient-specific and designed for theanatomy of the specific patient during the preoperative plan. Theconvertible guide 400 can include guiding formations for TKA pinregistration, including anterior guiding formations 410 at connectingportions between the anterior member 406 and the lateral and medialmembers 402, 404, and distal guiding formations 412 at connectingportions between the distal member 406 and the lateral and medialmembers 402, 404. The elongated member that is designed to engage thepartial knee guide 300, i.e., medial member 404 in the illustration ofFIG. 5, includes a connector or extension 414 having a tapered wall 416that can be received into the elongated slot 310 of the partial kneeguide 300 and mate with the tapered inner wall 306 of the slot 310. Thecorresponding medial distal guiding formation 412 is formed on theextension 414.

The frame structure of the elongated members 402, 404, 406, 408 providesa lightweight and inexpensive addition to the patient-specific kit of apatellofemoral procedure, although a different structure or shape, suchas the structure of the patient-specific guides for total kneearthroplasty can be used with the addition of a connector 414.

Referring to FIGS. 7 and 8, physical (plastic, for example) bone modelscreated as part of the preoperative plan can also be provided to thesurgeon in a kit with the patient-specific convertible guides and PFR orPKA guides describe above. The physical bone models have outerthree-dimensional surfaces replicating the actual outer bone surfaces ofthe specific patient and can help the surgeon mount the provided guidesthereon and/or visualize the resections and other procedures beforemounting the guides on the actual bone of the patient during theoperation. These physical bone models can be provided with a supportstructure that can receive a support element, such as a rod, so that thesurgeon can support the physical bone model without directly holding it,thereby providing a full three-dimensional view of the physical bonemodel. As an example, FIG. 7 illustrates an underside plan view of aphysical bone model 500 of the distal femur of a specific patient. Thephysical bone model 500 has an outer three-dimensional surface 510 thatreplicates the outer surface of the distal femur of the patient. Thesupport structure includes a central hub 506 supported by a number ofarms 504 extending from an inner wall 502 of a hollow underside surface503 of the bone model 500. The hub 506 can have a blind bore 508 forreceiving a holding member, such as the holding member 560 shown in FIG.8, for holding the bone model with the hollow underside surface 503facing downwards.

FIG. 8 illustrates a physical bone model 550 for a proximal tibial boneof the specific patient. The physical bone model 550 has an outerthree-dimensional surface 554 that replicates the outer surface of theproximal tibia of the patient. The bone model 550 can include a blindbore 552 for receiving a holding member 560 to hold the physical bonefor visualization of the resection and other alignment proceduresdetermined during the preoperative plan for the patient. The holdingmember 560 can be a rod, a bar or other holding structure. The holdingmember 560 can be held by hand or supported on an appropriate basemember 562 on a table or other surface.

The various patient-specific guides, other tools and physical bonemodels described herein can be manufactured by various stereolithographymethods, selective laser sintering, fused deposition modeling or otherrapid prototyping methods. In some embodiments, computer instructions oftool paths for machining the patient-specific guides and/or implants canbe generated and stored in a tool path data file. The tool path data canbe provided as input to a CNC mill or other automated machining system.

The guides and other tools can be made of polymer, ceramic, metal orother suitable material depending on the use, and sterilized as needed.The sterilized tools and bone models can be shipped to the surgeon ormedical facility in a kit for a specific patient and surgeon to be usedduring the surgical procedure.

The various embodiments of patient-specific convertible guides,patellofemoral guides, unilateral/unicondylar guides, drill templatesand other instruments can be provided in various combinations to thesurgeon and used to facilitate the conversion of a patient-specificpreoperative plan from one procedure to another intraoperatively, whileretaining the patient-specific guidance provided by the preoperativeplan. In this respect, the present teachings integrate preoperativelytwo different surgical procedures so that either one can be selectedintraoperatively as a patient-specific procedure without excessiveduplication.

Example embodiments are provided so that this disclosure is thorough,and fully conveys the scope to those who are skilled in the art.Numerous specific details are set forth such as examples of specificcomponents, devices, and methods, to provide a thorough understanding ofembodiments of the present disclosure.

It will be apparent to those skilled in the art that specific detailsneed not be employed, that example embodiments may be embodied in manydifferent forms and that neither should be construed to limit the scopeof the disclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail. Accordingly, individual elements or features of aparticular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A convertible patient-specific guide for use in aknee of a patient during either a partial knee arthroplasty or a totalknee arthroplasty comprising: a body having a patient-specificthree-dimensional undersurface designed preoperatively based on imagesof the patient's knee, the patient-specific threedimensional-undersurface closely mateable in only one position relativeto the knee and positively mating with a corresponding joint surface ofthe knee such that the patient-specific three dimensional-undersurfacenestingly fits about and within surface portions of the knee;patient-specific guiding formations extending from the body andconfigured for guiding surgical tools during either a total arthroplastyof the knee and a partial arthroplasty of the knee such that thearthroplasty to be performed is intraoperatively selectable; and whereinthe body includes a patient-specific severable portion comprising aportion of reduced thickness relative to the body, the severable portionin the form of a score line connecting first and second patient-specificportions of the body, the patient-specific severable portion designedpreoperatively from images to correlate to structure of the patient'sknee to permit use of the guide for a total knee arthroplasty when thebody is not severed, and to permit intraoperatively severing the firstportion and the second portion by breaking the guide on the severableportion such that the guide can be used to perform a partial kneearthroplasty after severing the first and second portion.
 2. Theconvertible patient-specific guide of claim 1, wherein thepatient-specific guiding formations include guiding formations for totalknee arthroplasty and partial patellofemoral arthroplasty.
 3. Theconvertible patient-specific guide of claim 1, wherein thepatient-specific guiding formations include guiding formations for totalknee arthroplasty and partial knee arthroplasty.
 4. The convertiblepatient-specific guide of claim 1, wherein the second portion, afterbeing severed from the first portion, defines a standalonepatient-specific patellofemoral guide.
 5. The convertiblepatient-specific guide of claim 4, wherein the second portion includes apatellofemoral guiding formation and distal guiding formations havingcovers.
 6. The convertible patient-specific guide of claim 5, whereinthe covers are removable for using the patient-specific guide in totalarthroplasty.
 7. The convertible patient-specific guide of claim 4,wherein the second portion includes structural features for supportingan anterior femoral resection block.
 8. The convertible patient-specificguide of claim 2 in combination with a patient-specific patellofemoralguide having a body with a patient-specific undersurface and guidingformations corresponding to corresponding distal guiding formations anda corresponding patellofemoral guiding formation of the convertiblepatient-specific guide.
 9. A convertible patient-specific guide for usein a patient during either a partial knee arthroplasty or a total kneearthroplasty comprising: a first body portion having a firstpatient-specific three-dimensional undersurface custom-made to match ananterior femoral knee joint surface of a specific patient such that thesurface is closely mateable in only one position with a correspondingjoint surface of the patient such that the patient-specific threedimensional-undersurface nestingly fits about and within surfaceportions of the joint surface in a single position relative to the knee,the patient-specific three-dimensional undersurface being constructedfrom images of the patient's knee; a second body portion having a secondpatient-specific three-dimensional undersurface custom-made to match adistal femoral surface of the patient such that the patient-specificthree dimensional-undersurface nestingly fits about and within surfaceportions of the joint surface in a single position relative to the knee,the patient-specific three-dimensional undersurface being constructedfrom the images of the patient, the second body portion connected to thefirst body portion along a frangible line of reduced thickness relativeto the first and second body portions, the frangible line configured forsevering the first body portion from the second body portionintraoperatively; a first plurality of patient-specific guidingformations extending from the first body portion for guiding componentsduring the arthroplasty; a second plurality of patient-specific guidingformations extending from the second body portion for guiding componentsduring the arthroplasty; and a patellofemoral patient-specific guidingformation extending from the second body portion, wherein the first andsecond pluralities of patient-specific guiding formations are configuredfor guiding a total knee arthroplasty; wherein the patellofemoralpatient-specific guiding formation is configured for guiding a partialpatellofemoral knee arthroplasty such that the total or partialpatellofemoral knee arthroplasty to be performed is intraoperativelyselectable by separating the first and second body portions along thefrangible line such that the partial patellofemoral knee arthroplasty isperformed after severing the first body portion from the second bodyportion; and wherein the frangible line is designed preoperatively fromthe images to correlate the frangible line to a structure of thepatient's knee.
 10. The convertible patient-specific guide of claim 9,further comprising a plurality of removable covers configured forselectively covering the second plurality of guiding formations.
 11. Theconvertible patient-specific guide of claim 10, further comprising asupport extending from the second body portion and including first andsecond slots configured to slidably receive corresponding legs of afemoral resection block.
 12. The convertible patient-specific guide ofclaim 11, in combination with a femoral resection block having first andsecond legs slidably received in the corresponding first and second legsof the support.
 13. The convertible patient-specific guide of claim 12,wherein the femoral resection block includes a cutting guide having acurved profile configured to wrap around a medial side of the patient'sfemur.
 14. The convertible patient-specific guide of claim 9, whereinthe first body portion includes a viewing window.
 15. A convertiblepatient-specific guide for use in a patient during either a partial kneearthroplasty or a total knee arthroplasty comprising: a first bodyportion having a first patient-specific three-dimensional undersurfacecustom-made to match an anterior femoral knee joint surface of thepatient such that the patient-specific three dimensional-undersurfacenestingly fits about and within surface portions of the knee in a singleposition relative to the knee, the patient-specific three-dimensionalundersurface being constructed from images of the patient, the firstbody portion including a viewing window and first and secondpatient-specific anterior guiding formations configured to guideanterior reference pins; and a second body portion having a secondpatient-specific three-dimensional undersurface custom-made to match adistal femoral surface of the patient such that the patient-specificthree dimensional-undersurface nestingly fits about and within surfaceportions of the knee in a single position relative to the knee, thepatient-specific three-dimensional undersurface being constructed fromimages of the patient, the second body portion connected to the firstbody portion along a frangible line of reduced thickness relative to thefirst and second body portions configured for severing the first bodyportion from the second body portion, the second body portion includingfirst and second patient-specific distal guiding formations configuredto guide distal reference pins and a patellofemoral guiding formationconfigured for guiding a patellofemoral reference pin, wherein the firstand second anterior guiding formations and the first and second distalguiding formations are intraoperatively selectable for total kneearthroplasty and the patellofemoral guiding formation isintraoperatively selectable for partial patellofemoral kneearthroplasty, the selection being made by intraoperatively breaking thefirst body portion from the second body portion along the frangibleline; wherein the frangible line is designed preoperatively from theimages to correlate the frangible line to a structure of the patient'sknee.
 16. The convertible patient-specific guide of claim 15, furthercomprising a support extending from the second body portion about thepatellofemoral guiding formation, the support including first and secondopposite slots for supporting a femoral resection block.
 17. Theconvertible patient-specific guide of claim 15, further comprising afemoral resection block having first and second legs slidably receivedin the corresponding first and second slots of the support.
 18. Theconvertible patient-specific guide of claim 15, further comprising firstand second covers configured for covering the first and second distalguiding formations when partial patellofemoral knee arthroplasty isintraoperatively selected.
 19. The convertible patient-specific guide ofclaim 15, wherein the anterior, distal and patellofemoral guidingformations include corresponding guiding bores.